This is a travesty
No real surprise only the extent.
Long Read from Salon
When asked if the missing receipts for Stepien and Miller seemed unusual, Brendan Fischer, director of the Federal Reform Program at the Campaign Legal Center (CLC), told Salon, "It doesn't surprise me at all. The Trump campaign has disguised millions of dollars in payments to personnel and vendors by routing the money through LLCs created or managed by senior Trump campaign officials."
https://www.salon.com/2020/09/08/short-on-cash-trump-campaign-appears-to-be-hiding-large-dollar-payments-to-top-staff/
Edit to clarify:
https://publicintegrity.org/politics/federal-election-commission-fec-to-effectively-shut-down/